Network service access method and access gateway equipment

ABSTRACT

The present invention includes a network service access method. In one embodiment, such a method comprises: forwarding the domain name resolution requests to a local domain name server of each Internet service provider providing services through access link corresponding with the Internet service provider; receiving Internet Protocol address on the domain name resolution requests which the local domain name server of each Internet service provider returned from the corresponding access link; selecting the Internet Protocol address according to line state of the access link of each Internet service provider providing services and returning the selected Internet Protocol address to the user equipments; and visiting network services by the access link of the Internet service provider returning the selected Internet Protocol address.

TECHNICAL FIELD

The invention relates to the field of communication, in particular to anetwork service access method and access gateway equipment.

BACKGROUND ART

At present Internet users can use the access links of multiple Internetservice providers (ISP) to access the network services. Each ISPprovides the users with its own Domain Name System (DNS) server andconverts the Domain Name into the Internet Protocol (IP) address withDNS service. In addition, the application service providers also publishtheir own network services with multiple ISP links and take over thedomain name resolution works with their own intelligent DNS server. Theapplication service provider 15 publishes its own network services (suchas WEB) with two ISP (marked as ISP1 and ISP2) networks (marked as 112and 122) and resolves its own domain name with its own intelligent DNSserver 152, as shown in FIG. 1. The rules for resolving domain names arewhen the source address requested by DNS is the IP address of the DNSserver 111 of ISP1, the intelligent DNS returns the IP address of thenetwork service on ISP1, while when the source address requested by DNSis the IP address of the DNS server 121 of ISP2, the intelligent DNSrequires to return the IP address of the network service on ISP2. Whenthe user equipments 14 (such as computers) are connected with the accesslinks 113 and 123 of ISP1 and ISP2 through the access gateway equipments13, multiple DNS servers IP can be set in the user equipments 14.However, the preferred DNS server is generally the only one selected toresolve the domain name, which means only if the preferred DNS server isfailed to resolve, will the user equipments 14 select other DNS serversto carry out the resolution. For example, if the preferred DNS server inthe user equipments 14 is the DNS server 111 of ISP1, the access gatewayequipments 13 will forward the domain name resolution requests to theDNS server 111 after they have received those requests of the networkservices sent by the user equipments 14, then the DNS server 111 willsend the domain name resolution requests to the intelligent DNS server151 of the application service provider 15 and the intelligent DNSserver 151 will return the IP address of the network services on ISP1 tothe DNS server 111 according to the foregoing domain name resolutionrules of the intelligent DNS server 151, then the IP address is sentform the DNS server 111 to the access gateway equipments 13 and isreturned from the access gateway equipments 13 to the user equipments14, and then the user equipments 14 will originate the network serviceaccess requests to the access gateway equipments 13 according to the IPaddress and the access gateway equipments 13 will visit the networkservices on the server 152 of the application service provider 15through the access link 113 of ISP1 after they have identified that theIP address belongs to ISP1. In the network structure shown in FIG. 1, ifthe DNS server 111 of ISP1 is set to be the preferred DNS server inmultiple user equipments 14 connected with the access gateway equipments13, all user equipments 14 will visit the network services through theaccess link 113 of ISP1, thereby causing overloads and congestion on theaccess link 113 of ISP1 and reducing the access speed of networkservices.

SUMMARY OF THE INVENTION

In view of the existing technical problems, the embodiment of thepresent invention provides a network service access method and accessgateway equipment, which can balance the loads on the access links ofdifferent service providers so as to improve the access speed of networkservices.

In order to solve the existing technical problems, the embodiment of thepresent invention proposes a network service access method whichcomprises:

receiving domain name resolution requests sent by user equipments;

forwarding the domain name resolution requests to a local domain nameserver of each Internet service provider providing services throughaccess link corresponding with the Internet service provider;

receiving Internet Protocol address on the domain name resolutionrequests which the local domain name server of each Internet serviceprovider returned from the corresponding access link;

selecting the Internet Protocol address according to line state of theaccess link of each Internet service provider providing services andreturning the selected Internet Protocol address to the user equipments;and

receiving network service access requests carrying the selected InternetProtocol address sent by the user equipments and visiting networkservices by the access link of the Internet service provider returningthe selected Internet Protocol address.

Accordingly, the embodiment of the present invention also proposes anaccess gateway equipment, which comprises:

a domain name resolution requests receiving module receiving the domainname resolution requests sent by the user equipments;

a forward module forwarding the domain name resolution requests receivedby the domain name resolution requests receiving module to the localdomain name server of each Internet service provider providing servicesthrough the access link corresponding with the Internet serviceprovider;

a network address receiving module receiving the Internet Protocoladdress on the domain name resolution requests which the local domainname server of each Internet service provider returned from thecorresponding access link after the forward module had forwarded thedomain name resolution requests;

a select module selecting the Internet Protocol address according to theline state of the access link of each Internet service providerproviding services after the network address receiving module hasreceived the Internet Protocol address and returning the selectedInternet Protocol address to the user equipments; and

a network service access module receiving the network service accessrequests carrying the selected Internet Protocol address sent by theuser equipments after the select module has returned the selectedInternet Protocol address to the user equipments and visiting thenetwork services by the access link of the Internet service providerreturning the selected Internet Protocol address.

In the implementation of the embodiment of the invention, the domainname resolution requests are forwarded to the local domain name serverof each service provider through the access link corresponding with theservice provider and the Internet Protocol address corresponding to thenetwork services returned by the local domain name server of eachservice provider is received so as to obtain the Internet Protocoladdress of the network services on different service provider networks;the Internet Protocol address is selected according to the line state ofthe access link of each service provider and is returned to the userequipments. The network service access requests carrying the selectedInternet Protocol address sent by the user equipments are received andthe network services are visited through the access link of the serviceprovider corresponding with the Internet Protocol address in the networkservice access requests, thereby balancing the loads on the access linksof different service providers so as to improve the access speed ofnetwork services.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the invention orthe technical programs in the existing technology, the embodiments orthe drawings needed to be used in the description of the existingtechnology will be briefly introduced. It's obvious for those skilled inthe art that the drawings described below are just some embodiments ofthe invention and can be used to obtain other drawings without thecreative works.

FIG. 1 is a schematic view of the network structure of the access linksof multiple Internet service providers visiting the network services;

FIG. 2 is a flow chart of a network service access method in theembodiment of the invention;

FIG. 3 is a structure diagram of an access gateway equipment in theembodiment of the invention; and

FIG. 4 is a schematic diagram of the interactive process between theaccess gateway equipments and the user equipments and the local domainname server of Internet service provider in the embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiment of the invention proposes a network service access methodand access gateway equipment that can balance the loads on the accesslinks of different service providers so as to improve the access speedof network services.

FIG. 2 is a flow chart of a network service access method in theembodiment of the invention, which includes:

Step 101: obtaining the Internet Protocol address of the local domainname server of each Internet service provider providing services;

Here, the access gateway equipments obtain the Internet Protocol addressof the local domain name server of each ISP providing services inadvance. For example, in the network structure shown in FIG. 1, ISP1 andISP2 are ISP providing services and the access gateway equipments 13 areconnected with the access link 113 of ISP1 and the access link 123 ofISP2 so that they respectively obtain the Internet Protocol addresses ofthe local domain name server 111 of ISP1 and the local domain nameserver 121 of ISP2. When implemented specifically, the access gatewayequipments 13 inquire and obtain the IP address of the local domain nameserver 111 through the access link 113 of ISP1, as well as that of localdomain name server 121 through the access link 123 of ISP2. When theaccess gateway equipments have obtained the IP address of the localdomain name server of each ISP providing services, the network serviceaccess method of the embodiment of the invention proceeds to step 102.

Step 102: receiving the domain name resolution requests sent by the userequipments;

Here, the access gateway equipments receive the domain name resolutionrequests for the network services sent by the user equipments, forexample, the domain name resolution requests for the name of somewebsite.

Step 103: forwarding the domain name resolution requests to the localdomain name server of each Internet service provider providing servicesthrough the access link corresponding with the Internet serviceprovider;

Here, when implemented specifically, the domain name resolution requestsare forwarded to the local domain name server of the Internet serviceprovider according to the Internet Protocol address of the local domainname server of the Internet service provider. For example, in thenetwork structure shown in FIG. 1, the access gateway equipments 13forward the domain name resolution requests to the local domain nameserver 111 through the access link 113 of ISP1 and to the local domainname server 121 through the access link 123 of ISP2. If the accessgateway equipments 13 are also connected with the access links of otherISP providing services, they forward the domain name resolution requeststo the local domain name server of the ISP through the access link ofthe ISP. For the local domain name server of other ISP without thecorresponding access link of ISP, it's not necessary for the accessgateway equipments to forward the domain name resolution requests to thelocal domain name server of the ISP.

Step 104: receiving the Internet Protocol address on the domain nameresolution requests which the local domain name server of each Internetservice provider returned from the corresponding access link;

Here, after the local domain name server of each ISP proving serviceshas received the domain name resolution requests sent by the accessgateway equipments, it will forward those requests to the intelligentDNS server of the application service providers and receive the IPaddress of the network services on the ISP network according to theforegoing domain name resolution rules of the intelligent DNS server andthen return the IP address to the access gateway equipments through thecorresponding access link. At this time, the access gateway equipmentscan obtain the Internet Protocol addresses of the network services ondifferent service provider networks. For example, in the networkstructure shown in FIG. 1, the access gateway equipments 13 receive theIP addresses which the local domain name server 111 and the local domainname server 121 respectively returned from the access link 113 of ISP1and the access link 123 of ISP2, and also the IP address of the networkservices on ISP1 and ISP2. In addition, the access gateway equipments 13can also establish the association relationship between the InternetProtocol address and the access link of the Internet service providerreturning the Internet Protocol address. For example, in the networkstructure shown in FIG. 1, the association relationship shown in Table 1can be established:

TABLE 1 access link IP address ISP1 IP1 ISP2 IP2

Step 105: selecting the Internet Protocol address according to the linestate of the access link of each Internet service provider providingservices and returning the selected Internet Protocol address to theuser equipments;

Here, when implemented specifically, the access gateway equipments canselect the Internet Protocol address according to the link absoluteresidual bandwidth, the proportion of residual bandwidth or the numberof connections of the access links of each service provider. In oneembodiment, step 105 may include the following sub-steps:

Step 1051: detecting the line state of the access link of each Internetservice provider providing services;

Step 1052: determining the access link used for visiting the networkservices according to the line state;

Here, in the network structure shown in FIG. 1, for example, the accessgateway equipments 13 detect that the absolute residual bandwidth of theaccess link 113 of ISP1 is lower than the preset congestion thresholdvalue and the absolute residual bandwidth of the access link 123 of ISP2is higher than the preset congestion threshold value, which means theloads on the access link 113 of ISP1 are bigger than those on the accesslink 123 of ISP2 and the access gateway equipments 13 now select theaccess link 123 of the network services on ISP2 as the access linkvisiting the network services. Also, the access gateway equipments 13detect that the absolute residual bandwidth of the access link 113 ofISP1 is lower than that of the access link 123 of ISP2, which also meansthe loads on the access link 113 of ISP1 are bigger than those on theaccess link 123 of ISP2 and the access gateway equipments 13 now selectthe access link 123 of ISP2 as the access link visiting the networkservices. Since the situations of determining the access links visitingthe network services according to the number of connections or otherjudgment conditions are similar to the forgoing ones, they are not bedescribed in detail.

Step 1053: obtaining the corresponding Internet Protocol addressaccording to the determined access link used for visiting the networkservices and the association relationship.

Here, the access gateway equipments obtain the IP address of the networkservices on the access link of the ISP as the IP address correspondingto the network services returned to the user equipments. For example, inthe network structure shown in FIG. 1, the association relationship canbe searched in Table 1 so as to obtain the IP address of the networkservices on the access link of the ISP. For example, if the access link123 of ISP2 is currently selected as the access link visiting thenetwork services, the association relationship is searched in Table 1 toobtain the IP address IP2 of the network services on the access link 123of ISP2.

Step 106: receiving the network service access requests carrying theselected Internet Protocol address sent by the user equipments andvisiting the network services by the access link of the Internet serviceprovider returning the selected Internet Protocol address.

Here, after the selected Internet Protocol address has been returnedfrom the access gateway equipments to the user equipments, the userequipments obtain the Internet Protocol address of the domain nameresolution requests sent in step 102 and then originate the networkservice access requests carrying the Internet Protocol address to theaccess gateway equipments. The access gateway equipments receive thenetwork service access requests carrying the Internet Protocol addresssent by the user equipments and visit the network services by the accesslink of the Internet service provider returning the selected InternetProtocol address. When implemented specifically, Table 1 can be searchedaccording to the Internet Protocol address in the network service accessrequests so as to obtain the access link of the corresponding Internetservice provider through which the network services are visited. Forexample, in the network structure shown in FIG. 1, the access gatewayequipments receive the network service access requests carrying theInternet Protocol address IP2 sent by the user equipments and theassociation relationship can be searched in Table 1 to obtain the accesslink 123 of the ISP of the network services on IP2 address.

FIG. 3 is a structure diagram of the access gateway equipment in theembodiment of the invention, which includes:

An obtaining module 31 is used to obtain the Internet Protocol addressof the local domain name server of each Internet service providerproviding services;

Here, the access gateway equipments obtain the Internet Protocol addressof the local domain name server of each ISP providing services inadvance. For example, in the network structure shown in FIG. 1, ISP1 andISP2 are ISP providing services and the access gateway equipments 13 areconnected with the access link 113 of ISP1 and the access link 123 ofISP2 so that they respectively obtain the Internet Protocol addresses ofthe local domain name server 111 of ISP1 and the local domain nameserver 121 of ISP2. When implemented specifically, the access gatewayequipments 13 inquire and obtain the IP address of the local domain nameserver 111 through the access link 113 of ISP1, as well as that of localdomain name server 121 through the access link 123 of ISP2.

A domain name resolution requests receiving module 32 is used to receivethe domain name resolution requests sent by the user equipments;

Here, the access gateway equipments receive the domain name resolutionrequests for the network services sent by the user equipments, forexample, the domain name resolution requests for the name of somewebsite.

A forward module 33 is used to forward the domain name resolutionrequests received by the domain name resolution requests receivingmodule 32 to the local domain name server of each Internet serviceprovider providing services through the access link corresponding withthe Internet service provider;

Here, when implemented specifically, the domain name resolution requestsare forwarded to the local domain name server of the Internet serviceprovider according to the Internet Protocol address of the local domainname server of the Internet service provider. For example, in thenetwork structure shown in FIG. 1, the access gateway equipments 13forward the domain name resolution requests to the local domain nameserver 111 through the access link 113 of ISP1 and to the local domainname server 121 through the access link 123 of ISP2. If the accessgateway equipments 13 are also connected with the access links of otherISP providing services, they forward the domain name resolution requeststo the local domain name server of the ISP through the access link ofthe ISP. For the local domain name server of other ISP without thecorresponding access link of ISP, it's not necessary for the accessgateway equipments to forward the domain name resolution requests to thelocal domain name server of the ISP.

A network address receiving module 34 is used to receive the InternetProtocol address on the domain name resolution requests which the localdomain name server of each Internet service provider returned from thecorresponding access link after the forward module 33 had forwarded thedomain name resolution requests;

Here, after the local domain name server of each ISP proving serviceshas received the domain name resolution requests sent by the accessgateway equipments, it will forward those requests to the intelligentDNS server of the application service providers and receive the IPaddress of the network services on the ISP network according to theforegoing domain name resolution rules of the intelligent DNS server andthen return the IP address to the access gateway equipments through thecorresponding access link. At this time, the access gateway equipmentscan obtain the Internet Protocol addresses of the network services ondifferent service provider networks. For example, in the networkstructure shown in FIG. 1, the access gateway equipments 13 receive theIP addresses which the local domain name servers 111 and 121respectively returned from the access link 113 of ISP1 and the accesslink 123 of ISP2, and also the IP address of the network services onISP1 and ISP2. In addition, the access gateway equipments 13 can alsoestablish the association relationship between the Internet Protocoladdress and the access link of the Internet service provider returningthe Internet Protocol address. For example, in the network structureshown in FIG. 1, the association relationship shown in Table 1 can beestablished.

After the network address receiving module 34 has received the InternetProtocol address, a select module 35 is used to select the InternetProtocol address according to the line state of the access link of eachInternet service provider providing services and return the selectedInternet Protocol address to the user equipments;

Here, when implemented specifically, the access gateway equipments canselect the Internet Protocol address according to the link absoluteresidual bandwidth, the proportion of residual bandwidth or the numberof connections of the access links of each service provider. The selectmodule 35 specifically includes:

A detection unit 351 is used to detect the line state of the access linkof each Internet service provider providing services;

A determining unit 352 is used to determine the access link used forvisiting the network services according to the line state detected bythe detection unit 351;

Here, in the network structure shown in FIG. 1, for example, the accessgateway equipments 13 detect that the absolute residual bandwidth of theaccess link 113 of ISP1 is lower than the preset congestion thresholdvalue and the absolute residual bandwidth of the access link 123 of ISP2is higher than the preset congestion threshold value, which means theloads on the access link 113 of ISP1 are bigger than those on the accesslink 123 of ISP2 and the access gateway equipments 13 now select theaccess link 123 of the network services on ISP2 as the access linkvisiting the network services. Also, the access gateway equipments 13detect that the absolute residual bandwidth of the access link 113 ofISP1 is lower than that of the access link 123 of ISP2, which also meansthe loads on the access link 113 of ISP1 are bigger than those on theaccess link 123 of ISP2 and the access gateway equipments 13 now selectthe access link 123 of ISP2 as the access link visiting the networkservices. Since the situations of determining the access links visitingthe network services according to the number of connections or otherjudgment conditions are similar to the forgoing ones, they are not bedescribed in detail.

An address acquisition unit 353 is used to obtain the correspondingInternet Protocol address in the association relationship establishingunit according to the access link used for visiting the network servicesdetermined by the determining unit 352.

Here, the access gateway equipments obtain the IP address of the networkservices on the access link of the ISP as the IP address correspondingto the network services returned to the user equipments. For example, inthe network structure shown in FIG. 1, the association relationship canbe searched in Table 1 so as to obtain the IP address of the networkservices on the access link of the ISP. For example, if the access link123 of ISP2 is currently selected as the access link visiting thenetwork services, the association relationship is searched in Table 1 toobtain the IP address IP2 of the network services on the access link 123of ISP2.

A network service access module 36 is used to receive the networkservice access requests carrying the selected Internet Protocol addresssent by the user equipments after the select module 35 has returned theselected Internet Protocol address to the user equipments and visit thenetwork services by the access link of the Internet service providerreturning the selected Internet Protocol address.

Here, after the selected Internet Protocol address has been returnedfrom the access gateway equipments to the user equipments, the userequipments obtain the Internet Protocol address of the sent domain nameresolution requests and then originate the network service accessrequests carrying the Internet Protocol address to the access gatewayequipments. The access gateway equipments receive the network serviceaccess requests carrying the Internet Protocol address sent by the userequipments and visit the network services by the access link of theInternet service provider returning the selected Internet Protocoladdress. When implemented specifically, Table 1 can be searchedaccording to the Internet Protocol address in the network service accessrequests so as to obtain the access link of the corresponding Internetservice provider through which the network services are visited. Forexample, in the network structure shown in FIG. 1, the access gatewayequipments receive the network service access requests carrying theInternet Protocol address IP2 sent by the user equipments and theassociation relationship can be searched in Table 1 to obtain the accesslink 123 of the ISP of the network services on IP2 address.

FIG. 4 is a schematic diagram of the interactive process between theaccess gateway equipments and the user equipments and the local domainname server of the Internet service provider in one embodiment of theinvention. In the embodiment, taking the network structure shown in FIG.1 for example, the interactive process includes the following steps:

Step 401: the access gateway equipments 13 obtain the Internet Protocoladdress of the local domain name server of each Internet serviceprovider providing services;

Step 402: the user equipments 14 send the domain name resolutionrequests to the access gateway equipments 13;

Step 403: the access gateway equipments 13 receive the domain nameresolution requests sent by the user equipments 14;

Step 404: the access gateway equipments 13 forward the domain nameresolution requests to the local domain name server 111 of ISP1 throughthe access link 113 of ISP1 and to the local domain name server 121 ofISP2 through the access link 123 of ISP2;

Here, after the local domain name server of each ISP proving serviceshas received the domain name resolution requests sent by the accessgateway equipments, it will forward those requests to the intelligentDNS server of the application service providers and receive the IPaddress of the network services on the ISP network according to theforegoing domain name resolution rules of the intelligent DNS server andthen return the IP address to the access gateway equipments through thecorresponding access link. At this time, the access gateway equipmentscan obtain the Internet Protocol addresses of the network services ondifferent service provider networks.

Step 405: the access gateway equipments 13 receive the IP addresseswhich the local domain name server 111 of ISP1 and the local domain nameserver 121 of ISP2 respectively returned from the access link 113 ofISP1 and the access link 123 of ISP2;

Step 406: the Internet Protocol address is selected according to theline state of the access link 113 of ISP1 and the access link 123 ofISP2 and the selected Internet Protocol address is returned to the userequipments 14;

Step 407: the user equipments 14 originate the network service accessrequests carrying the selected Internet Protocol address to the accessgateway equipments 13;

Step 408: the access gateway equipments 13 receive the network serviceaccess requests carrying the selected Internet Protocol address sent bythe user equipments 14 and visit the network services of the applicationservice provider 15 by the access link of the Internet service providerreturning the selected Internet Protocol address.

To sum up, the domain name resolution requests are forwarded to thelocal domain name server of each service provider through the accesslink corresponding with the service provider and the Internet Protocoladdress corresponding to the network services returned by the localdomain name server of each service provider is received so as to obtainthe Internet Protocol address of the network services on differentservice provider networks; the Internet Protocol address is selectedaccording to the line state of the access link of each service providerand the selected Internet Protocol address is returned to the userequipments. The network service access requests carrying the selectedInternet Protocol address sent by the user equipments are received andthe network services are visited through the access link of the serviceprovider corresponding with the Internet Protocol address in the networkservice access requests, thereby balancing the loads on the access linksof different service providers so as to improve the access speed ofnetwork services.

What is disclosed above is only a preferred embodiment of the inventionand certainly can not be used to limit the scope of the invention, sothe same changes made in accordance with the claims of the invention arestill covered by the scope of the invention.

What is claimed is:
 1. A network service access method, comprising:receiving domain name resolution requests sent by user equipments;forwarding the domain name resolution requests to a local domain nameserver of each of multiple Internet service providers providing servicesthrough an access link corresponding with each of the Internet serviceproviders; receiving an Internet Protocol address on the domain nameresolution requests which the local domain name server of each of theInternet service providers returned from the corresponding access link;selecting the Internet Protocol address according to a line state of theaccess link of each of the Internet service providers providing servicesand returning the selected Internet Protocol address to the userequipments; and receiving network service access requests carrying theselected Internet Protocol address sent by the user equipments andvisiting network services by the access link of the Internet serviceprovider returning the selected Internet Protocol address.
 2. Thenetwork service access method according to claim 1, further comprising,before the step of receiving the domain name resolution requests sent bythe user equipments: obtaining the Internet Protocol address of thelocal domain name server of each Internet service provider providingservices.
 3. The network service access method according to claim 2,wherein the step of forwarding the domain name resolution requests tothe local domain name server of each Internet service provider providingservices further comprises: forwarding the domain name resolutionrequests to the local domain name server of the Internet serviceprovider according to the Internet Protocol address of the local domainname server of the Internet service provider.
 4. The network serviceaccess method according to claim 3, wherein the step of receiving theInternet Protocol address on the domain name resolution requests whichthe local domain name server of each Internet service provider returnedfrom the corresponding access link further comprises: establishing theassociation relationship between the Internet Protocol address and theaccess link of the Internet service provider returning the InternetProtocol address.
 5. The network service access method according toclaim 4, wherein the step of selecting the Internet Protocol addressaccording to the line state of the access link of each Internet serviceprovider providing services further comprises: detecting the line stateof the access link of each Internet service provider providing services;determining the access link used for visiting the network servicesaccording to the line state; and obtaining the corresponding InternetProtocol address according to the determined access link used forvisiting the network services and the association relationship.
 6. Anaccess gateway equipment, comprising: a domain name resolution requestsreceiving module receiving the domain name resolution requests sent byuser equipments; a forward module forwarding the domain name resolutionrequests received by the domain name resolution requests receivingmodule to a local domain name server of each of multiple Internetservice providers providing services through an access linkcorresponding with each of the Internet service providers; a networkaddress receiving module receiving an Internet Protocol address on thedomain name resolution requests which the local domain name server ofeach of the Internet service providers returned from the correspondingaccess link after the forward module had forwarded the domain nameresolution requests; a select module selecting the Internet Protocoladdress according to a line state of the access link of each of theInternet service providers providing services after the network addressreceiving module has received the Internet Protocol address andreturning the selected Internet Protocol address to the user equipments;and a network service access module receiving the network service accessrequests carrying the selected Internet Protocol address sent by theuser equipments after the select module has returned the selectedInternet Protocol address to the user equipments and visiting thenetwork services by the access link of the Internet service providerreturning the selected Internet Protocol address.
 7. The access gatewayequipment according to claim 6, further comprising: an obtaining moduleobtaining the Internet Protocol address of the local domain name serverof each Internet service provider providing services.
 8. The accessgateway equipment according to claim 7, wherein the forward moduleforwards the domain name resolution requests to the local domain nameserver of the Internet service provider according to the InternetProtocol address of the local domain name server of the Internet serviceprovider.
 9. The access gateway equipment according to claim 8, whereinthe network address receiving module comprises: an associationrelationship establishing unit establishing the association relationshipbetween the Internet Protocol address and the access link of theInternet service provider returning the Internet Protocol address. 10.The access gateway equipment according to claim 9, wherein the selectmodule further comprises: a detection unit detecting the line state ofthe access link of each Internet service provider providing services; adetermining unit determining the access link used for visiting thenetwork services according to the line state detected by the detectionunit; and an address acquisition unit obtaining the correspondingInternet Protocol address in the association relationship establishingunit according to the access link used for visiting the network servicesdetermined by the determining unit.